<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script>
        var id=10;//数值
        var username="tom";//字符串string
        var isMarried=true;//布尔值boolean
        var a;
        let c;
        var b=null;
        var arr=[1,2,3];//定义数组
        console.log(typeof id);//number
        console.log(typeof username);//string
        console.log(typeof isMarried);//boolean
        console.log(typeof a);//undefined
        console.log(typeof c);//undefined
        console.log(typeof b);//object
        console.log(typeof arr);//object





    </script>
</head>
<body>

</body>
</html>